1. Field of the Invention
This invention relates to axial flow threshing and separating machines and more particularly to such machines having devices for adjusting the concaves with respect to the threshing rotors.
2. Description of the Prior Art
In U.S. Pat. No. 3,631,862 assigned to Sperry Rand Corporation, there is disclosed an axial flow threshing and separating machine in which the concaves are adjusted with respect to the associated threshing rotors by cams disposed at respective ends of the concaves, rotation of the cams effecting the desired raising or lowering of the concaves relative to the threshing rotors. The cams are rotated through the use of rods and cranks, considerable force being necessary to actuate the same in the event the threshing rotors becomes jammed. Jamming can occur in combine harvesters, for example, when the crop material bunches or is fed in lumps which can happen when the crop is wet. When blockages occur, appreciable forces are exerted on the concaves and the supporting devices associated therewith. These forces give rise to high frictional resistance which must be overcome in order to rotate the cams with the consequence that, when a combine harvester is operating, it is difficult to lower the concaves relative to the threshing rotors in order to remove the blockage.
A further disadvantage of the known concave adjusting device lies in the fact that the cams and the associated supporting devices on the machine frame are subject to pronounced wear. This also applies to the longitudinal slots in the side panels of the combine harvester in which the shafts attached to the cams are carried, since considerable forces are exerted at these locations along the edges of the slots. In addition, dust and other debris may penetrate the longitudinal slots and/or block up the slots, whereby adjustment of the height of the concaves is impeded or even rendered impossible.